Tuesday, December 23, 2014

Another project

I blame TV -- specifically, Cafe Racer TV -- I've been able to watch all of Season 4 due to a online download program.  I was inspired to build another bike.  Not sure if it will be a streetbike, or a trackbike, but it will be minimalist, and cafe-inspired.

The basis will be my old Muz frame -- not the lightweight tigcraft one, but the actual MZ streetbike frame with a vin I got years ago.  I was going to put a DRZ engine into it, but stopped the project when racing became a priority.  I also had a RGV125 swingarm set up to work with a 17mm swingarm pivot, and roller bearings from again, a DRZ400.

My vision had spoked wheels, no fairing (either a numberplate, a headlight, or both), and a simple aircooled single cylinder engine -- a xt or tt 600.  One finally came up on ebay for a good price -- $300.  It's an 83, but like most of these engines, little has changed over the years.  The tank is always a problem, but I'd heard someone built one with a mito or 916 tank.  Google pics came up with this:

The seat subframe is not stock, but it does mount to the stock locations on the frame.  This has the liquid cooled version of the engine, so mine will be missing a radiator on the front (hooray!).  Oil tank I think is custom, and under the seat.  Both the liquid and air-cooled engines are dry sump.

Taking some pictures of complete Muz bikes, and figuring out how the RG swingarm would fit, I sketched out the following:

A bit rough, but its a start.  Rear suspension mimics that of an ex650, as it is off to the right hand side, with mounted welded to the swingarm hump, and the frame tube.  I am making an educated guess that a 900ss shock from a Ducati should be close on the spring rate and valving.

With that in mind, in an orgy of fortuitous ebay shopping, I ticked a bunch of things off the list:

The XT engine itself.  Comes bare with just a minimal amount of wiring.  I am still unclear whether this is an XT or TT engine.  One has a lighting alternator for street use, whereas the other has a bit more hp due to a hotter cam.  Fitting lights is not impossible either way.

Forks... 99-02 R6 forks slot into the MZ frame with a bearing swap... from a DRZ of all things!  Clip ons will be above the triple, and this comes with an axle and spacers which is a bonus.

Shock -- an OEM Showa from a 900ss.  Better than the Sachs that came stock.  Main use is to fabricate the shock mounts on the frame and swingarm.

Finally, the wheels.  These are Behr supermoto wheels for a KTM, but some research indicates that the KTM wheels (particularly the rear) will fit a DRZ swingarm... and the rg swingarm is the same width.  Finally the engine can be moved to the left or right somewhat to perfectly line up the sprockets.  Front axle is 26mm, which will require some sleeves, but spacers will be needed anyway to fit in the r6 forks, so some captured spacers could be fabbed up to work.  Oversize front rotor is nice, but I need to source a rear sprocket and rotor.

So, a lot to do, but it should be challenging and fun.  Frame and swingarm is at the sandblasters right now, as some welding will no doubt be needed, and it is best to work with a bare frame to start.

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